There are vast zones of clay soils which are generally extracted up to 3m deep (active layer). Owing to humidity variations throughout the year, this type of soil causes much damage to structures due to continuous changes in volume. Very often the clay is discarded and substituted by inert materials at the construction stage. The use of hydrated lime with this type of soil is a treatment that aims to inhibit the already volumetric instability by using the resulting mixture as inert material (Nelson, J.D., Miller, D.J.: Expansive Soils, Problems and Practice in Foundation and Pavement Engineering. John Wiley & Sons, Inc., USA, (1992)). Additionally, it is known that such a mixture also improves the strength properties, and it is possible to use it as a resistant inert composite, at low cost, for construction material. Nevertheless, due to the lack of tracking of this composite over time, safety issues related to the durability of such properties are uncertain. Because of the above, in this work, the composite was subjected to a constant exposure to temperature to simulate the evolution process of the composition on a laboratory scale, assuming that the acquired properties originate from the mineralogical composition created at the time of the sample. The permanence of such composition is associated to the properties acquired since the beginning.